Milo g



(No Model.)

M. G. KELLOGG. MULTIPLE SWITGHBOARD.

Patented Oct. 26, 1897.

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Nrrnn STATES PATENT rrrcn.

MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG SWITCIIBOARD AND SUPPLYV COMPANY, OF SAME PLACE.

lVIULTIPLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 592,335, dated October 26, 1897.

Application filed December 12, 1889. Serial No. 333,538. (No model.)

T0 all whom it may concern,-

Be it known that I, MrLo G. KELLOGG, of Chicago,lllinois,temporarily residing at Stuttgart, in the Empire of Germany, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchan ges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this speciiication.

My invention relates to a telephone-eX- change system in which the subscribers lines are metallic-circuit lines; and it consists in a system of calling, switching, and testing such lines which I shall describe and claim.

I place as many switchboards in the central office as are found necessary in order to properly operate the exchange. On each board for each line is a spring-jack or similar switch having two contact-points which are normally in contact and a third contact-piece insulated from the rest, (except by the circuit connections,) said switch being adapted to receive a loop-switch plug and, when a plug is inserted, to disconnect the contact-points which are normally in contact and connect one of them with one contact-piece of the plug and the other contact-piece of the plug with the third contact-piece of the switch mentioned above. These third contact-pieces are also so placed and arranged that a test-plug may readily be applied to them.

Figures l and lb of the drawings are sections of two multiple switchboards to which the same lines are connected. Fig. 2 is a diagram of the boards and the circuits and connections to them necessary to illustrate my invention. Fig. 3 is an operators cord system adapted for use with the boards. Fig. 4 is a diagram of the subscribers-station apparatus necessary to illustrate my invention. Fig. 5 shows an operators test system.

In the drawings like parts and apparatus are indicated by the same letters and figures of reference.

G in each case represents a ground connection. y

In Fig. 2, A is a sectional view7 of the switchboard shown in Fig. la, and A' is a sectional view of the switchboard shown in Fig. lb, each as indicated by the line d c. a b represent rubber strips on which the metal parts of the switches are mounted, as shown. are square holes through the fronts of the strips,adapted to receive and guide the switchplugs. The contact-springs g g are mounted to the rear of the holes and normally bear on their corresponding contact-points h h. j j are the contact-pieces of the switches, insulated from the rest, (except by the circuit connections.) The switch-plugs are shown in Fig. 3 and marked D D. When a plug is inserted into a switch, it disconnects the spring g of the switch from its corresponding contact-point h and the two contact-pieces of the plug form connection with the spring and with the contact-piece j, respectively.- Each section of `a rubber strip, with its contact spring, point, and insulated piece and the hole, all arranged and operating as above, may be considered as a spring-jack switch.

w and @c in Fig. 2 are calling-annunciators for the lines. Two lines are shown in the figure as connected to the boards. The two branches of one line are marked line No. l and line No. lb, respectively, and the two branches of the other line are marked line No. 2a and line No. 2b. The circuit of a line may be traced as follows: One branch, starting out from the subscribers station, passes tothe central office and through the pairs of contact-points g h of its switches, passing in each case to the spring first. It then passes through its line-annunciator and thence to the ground. The other branch of the line is connected to all the contact-pieces j j of its switches.

In the operators cord system shown in Fig. 3, D D represent a pair of loop-switch plugs. n n is the rubber insulation, and m m are the contact-pieces of the plug. They extend to Vthe bottom of the plug, as shown, and are adapted to rest normally on the metal strip o, which thereby temporarily connects them together.

Y is the looping-in switch for the pair of cords, having three pairs of contact-bolts, on which the operator may at will place the levers of the switch. 'v is the clearing-out annunciator of the pair of cords. B is the operators calling generator or battery, and t is her telephone. The circuits and connec- IOO tions are substantially as shown. Each operator should have a cord system with as many pairs of cords and plugs and their switches and annunciators as she may need. Y She will need only one calling-generator and one telephone, and their connections with the other parts, as well as the method of operating the system in connection with the boards, will be apparent to those skilled in the art.

, In the subscribers-station apparatus shown in Fig. 4, l is the calling-generator. 2 is the signal-bell. 3 is the transmitter. 4c is the primary, a'nd 5 is the secondary, of the inductioncoil. 6 is the transmitter-battery. 7 is the telephone-switch, and 8 is the hand-telephone. These parts may be usual forms of apparatus and are connected as shown or in other way to produce the required results.

The signal-bell is an ordinary vibrating bell, (having an automatic circuit-breaker,) as shown, and of the resistance suitable to the circuit.

The calling-generator has a modified construction and is as follows: It has an automatic device,shown in the drawings,by which, when the crank is not in motion, the wire 0f the armature is shunted and the line is disconnected from the ground at the subscribers station, andwhen the vcrank is in motion the shunt is taken from the armature and the line is temporarily connected with the ground at the subscribers station.

The automatic device shown is a modification of a form very generally used, the modification being substantially in the arrangement of the contact-points.

wheel, a pinin the shaft which engages in t-he V-shaped arrangement, and a spring which presses against the wheel and brings the pin normally in the center of the V-shaped arrangement. The contact-points are substantially as shown. The spring is marked p, one of the contact-points q, and the other point r. When the generator is not operated,the spring bears on point q. When the generator is being operated, the pin in its shaft presses on one of the sides of the V-shaped arrangement and presses the driving-wheel in the spring and carries the spring away from contact-point q and into connection with point r. Point r is connected with the ground. The spring is connected to the metal fra-me of the generator. One side of the armature-coil and one side or branch, as wire No. l", of the metallic circuit are connected to the metal frame. The other side ofthe armature-,coil is connected to an insulated piece on the armatureshaft, against which the insulated contactspring, marked sbears. This spring is connected to the other side or'branch of the line, marked wire No. la, and is also connected to the point q. The armature-coil is therefore shunted by a circuit,while the generator is not. operated, and when it is operated this shunt connection is open by the opening of points p q. The line is normally disconnected with It consists in a V- shaped attachment to the hub of the drivingthe ground at thev subscribers station, but when the generator is operated it is temporarily grounded there by the closing of points p fr, with the armature-coil between such connection and the ground connection of the line at the central ofiice.

I have represented in the subscribers-station apparatus the gravity telephone-switch ordinarily used. The contacts and circuits are Stich that when the hand-telephone is on the switchthetelephoneis switchedorshunted from the direct circuit of the line and the signal-bell isin the direct circuit, and when the telephone is off from the switch it is in the direct circuit of the line and the signal-bell is not in the direct circuit.

In the drawings, Fig. 4, wire No. l and wire No. lb represent the two sides or branches of a line, and G is the ground connection. The generatorshould be so connected into the circuit that the temporary connection y made between the line and the ground is between the normally open end of the line and the armature-coil. When the subscribers telephone is on his switch, the vibrating bell' 2 is in the direct circuit of the line, the circuit being as follows: from wire No. 1b through bell, shunt around generator, transmitter,v

connection with any contact-piece j at itsv board, t is a test receiving instrument, and B is a test-battery. The connections are substantially as shown. Each operator has a test system and it is conveniently mounted and arranged for her work. y The operation of the test system is as follows: When an operator tests a line by placing her test-plug into contact with the contest-piece j of the line, and the line is not switched at any board and the subscribers telephone is not taken from its switch for use, the signal-bell (which is then in the circuit) will vibrate and the operator will hear the m'ake and break in her instrument, and she thereby knows that the line is free and may be connected to. Should, however, the line be switched at any board and the IOO IOS

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ground connection of the line at the central .switched for use. In some multiple-test systems the line tests busy only when it is switched at some board, andit may test free and be connected to when the subscriber has Y already sent in his call and taken his telephone for use and cause him annoyance and confusion. In other systems the line tests only when the subscribers telephone is switched for use, and it may test free and be connected to when his telephone is on its switch, but the line is still in connection with another line, causing annoyance and .confusion to the subscribers and to the office. My system obviates both these sources of dissatisfaction in the operation of an exchange system.

The circuits in Fig. 4 show the bell 2 when the telephone is off the switch in one branch of a circuit containing two branches, one of which contains the transmitter 3, the primary of the in duction-coil, and the subscribers battery 6, and the other of which is a circuitwire of small resistance, which is practically a short circuit to the bell. The battery should be merely sufficient to operate the transmitter, and the bell should be of a resistance of considerable size, suitable for the main-line circuit in which it is to be operated, and, being shunted as described, the bell would not be operated when thus connected with the subscribers battery even when the test-battery at the central office is connected to the line.

The test-batteries should be strong enough to operate the circuit-breakers and test receiving instruments through the test-circuits, as described. When the test-current passes through the line annunciators, it should, however, be such as not to operate them. The annunciators may be polarized annunciators constructed to be operated by only one polarity of current, and they and the testbatteries may be connected into the circuits so that the polarity of the batteries is not such as to operate the annunciators.

I claim as my invention and desire to secure by Letters Patentl. A test-circuit for a metallic-circuit line,

from the ground, through a test receiving instrument to a test plug or device, thence to one side or branch of the line when the test is applied, thence through the circuit of the line and a pair of switch contact-points normally closed but open while the line is switched for use by the switch which controls them, to the ground, in combination with a circuitbreaker at the subscribers station normally included in said test-circuit a subscribers telephone its switch-contacts and circuit connection controlled thereby whereby when .the telephone is not switched for use the circuitbreaker is included in the circuit, and when the telephone is switched for use the circuitbreaker is switched or shunted from the direct circuit, and a battery in said circuit, substantially as set forth.

2. A test-circuit for a metallic-circuit line, from the ground, through a test receiving instrument to a test plug or device, thence to one side or branch of the line when the test is applied, thence through the circuit of the line and pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, to the ground, in combination with a circuit-breaker at the subscribers station normally included in said test circuit, a subscribers telephone, its switch-contacts and circuit connections controlled thereby whereby when the telephone is not switched for use the circuit-breaker is included in the circuit and when the telephone is switched for use the circuit-breaker is switched or shunted from the direct circuit, and a battery in said circuit, substantially as set forth.

3. A 'test-circuit for a metallic-circuit line, from one side or branch of the line, through the circuit of the line and a pair of switch contact-points normally closed but open while the line is switched for use by the switch which controls them, to one side of each of several test receiviuginstruinents in multiple or parallel circuit, said instruments being placed, one at each of several boards and each having on its other side a test plug or device adapted to be brought for testing into connection with said side or branch of the line, in combination with a circuitbreaker at the subscribers station, a switch with contact-points which switch the circuit-breaker into his line while his telephone is not switched for use and out of the circuit while the telephone is switched for use, and a battery in any test-circuit established, substantially as set forth.

4. A test-circuit for a subscribers line,from one side or branch of the line, through the circuit of the line and pairs of contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, to one side of each of several test receiving instruments in multiple or parallel circuit, said instruments being placed one at each of the boards and each hav- IOO IIO

ing on its other side a test plug or device v adapted to be brought for testing into connection with said side or branch of the line, in combination with a circuit-breaker at the subscribers station, a switch with contactpoints which switch the circuit-breaker into his line while his telephone is not switched for use and out of the circuit while the telephone is switched for use, and a battery in any test-circuit established, substantially as set forth.

5. A test-circuit for a metallic-circuit line, from the ground, through a battery and a test receiving instrument to a test plug or device, thence to one side or branch of the line while the test is applied, thence through the circuit of the line and a pair of switch contact-points normally closed but open while the line is switched by a switch which controls them, in combination with a circuit-breaker at the subscribers station, and a switch with contactpoints which switch the circuit-breaker into set forth.

6. A test-circuit for a metallic-circuit line, from one side or branch of the line, through the circuit of the line and a pair of switch contact-points normally in contact but open while the line is switched by a switch which controls them, thence to one side of a test receiving instrument and through it to a test.

plug or device adapted to be brought for testinginto connection with said side or branch of the line, a battery in the circuit between said pair of contact-points and saidswitch-plug, a circuit-breaker at the subscribers station and a switch with contact-points which switch the circuit-breaker into his line-circuit while his telephone is not switched for use and out of the circuit while it is switched for use, substantially as set forth. v

7. A test-circuit for a metallic-circuit lin containing a test-battery from the ground, through a test receiving instrument to a test plug or device, thence to one side or branch of the line when the test is applied, thence through the circuit of the line, a pair of switch contact-points normally in contact but open while the line is switched by a switch which controls them, and an annunciator, to the ground, in combination with a circuitbreaker at the subscribers station normally in thetest-circuit a subscribers telephone its switch and contact-points and connections controlled thereby, whereby the circuitbreaker is included in the direct circuit when otherwise, said test battery and instruments being so constructed and connected that when a test is applied it will not operate said annunciator but will operate said test receiving instrument when it is in closed circuit with the circuit-breaker, substantially as set forth.

8. A test-circuit for a metallic-circuit line containing a test-battery from one side or4 v branch of the line, through the circuit of the line, a pair of switch contact-points normally in contact but open while the line is switched by a switch which controls them and an annunciator, to one side of a test receiving instrument and through it to a test plug or device adapted to be brought for testing into connection with said side or branch of the line, in combination with a circuit-breaker contact points which switch the circuitbreaker v at the subscribers station into the line while the subscribers telephone is not switched for use and out of the direct circuit of the line while the telephone is switched for use, said battery and instruments being so constructed and connected that when a test is applied it will not operate said annunciator but will operate said test receiving instrument when in closed circuit with the circuitbreaker, substantially as set forth.

9. In a telephone-exchange system, a metallic-circuit line normally passing, on one of its sides, successively, through pairs of contact-points, one pair on each of several switchopen While the line is switched at their board,

and thence to the ground, in combination with a test wire or circuit grounded on one end, containing a test receiving instrument and battery and connected on its other end to a test plug or device adapted to be brought for testing into connection with the other side of the line, and a circuit-breaker at the subscribers station in the circuit of his line while his telephone is not switched for use but not otherwise,substantially as set forth.

1 0. In a telephone-exchange system, a metallic-circuit line normally passing on one side, successively, through pairs of contactpoints normally in contact but open while the line is switched at their board, and thence to the ground, in combination with test receiving instruments, one at each board where a pair of said contact-points is located, each instrument being grounded on one side and connected on the other side to a test plug or device adapted to be brought for testing into connection with the other side of the line, a battery in circuit with each instrument between the switch contact-points and its testplug, a circuit-breaker at the subscribers station and a switch with contact points which switch the circuit-breaker into the circuit of the linev while his telephone is not switched for use and out of the circuit while 4it is switched for use, substantially as set `forth. the telephone is not switched for use but not ll. In a telephone-exchange system, multiple switchboards, a metallic line connected to the same and one of its sides or branches normally groundedv at the central office, and

' switching devices to connect said line at any board with another line for conversation and when thus connected to disconnect it from the ground, in combination with test receiving instruments, one at each board, grounded on v7o boards, each pair4 normally in contact butl IOO IIO

one side and connected on the other side to for testing into connection with the other yside of said line, a battery in the test-circuit thereby established, and a circuit-breaker at `the subscribers station in the circuit of the line while his telephone is not switched for ,use but not otherwise, substantially as set lforth normally in said circuit, and a switch with 2 12. In a telephone-exchange system, metalthe other side of the line, a battery in the circuit between the switch contact-points and each test-plug, and a circuit-breaker in the circuit at the subscribers station when his telephone is not switched for use but not otherwise, substantially as set forth.

13. In a telephone-exchange system, multiple switchboards, a metallic-circuit line connected to the same and one of its sides or branches normally grounded at the central oiiice through an annunciator, and switching devices to connect said line with another line for conversation and when thus connected to disconnect it from the ground and the annunciator, in combination with test receiving instruments, one at each board and each grounded on one side and connected on its other side to a test plug or device adapted to be brought into connection with the other side of the line for testing, a battery in the test circuit thereby established a circuit breaker at the subscribcrs station in the direct circuit of the line while the line is not in use, the subscribers telephone, its switch and contacts and connections controlled thereby whereby the circuit-breaker is switched or shunted from the direct circuit of the linc when the telephone is switched for use but not otherwise, said battery and instruments being so constructed and connected that when a test is applied it will not operate said annunciator but will operate said test receiving instrument when in closed circuit with the circuit-breaker;substantially as set forth. MILO G. KELLOGG. Witnesses:

FRANCES D. KELLOGG, ELrsE IILZER. 

